Field of present invention relates to scales and other weighing devices such as those, for example, located at and combined with a data reader device into a scanner-scale system.
Data readers such as bar code scanners typically include a scale apparatus for measuring weights of produce and other items sold by weight. The scale apparatus typically has a load cell and a weigh platter which rests on the load cell. The weigh platter is typically flush mounted with the top surface of a checkout counter. Such a flush mounted weigh platter exposes the scale to inaccurate weighing when articles placed on the scale extend beyond the perimeter of the scale surface and onto the checkout counter. In such a situation, where the item comes to rest partly on the top surface of the checkout counter the scale would record a weight less than the actual weight of the item, namely a lower weight than the item actually weighs resulting in a loss of revenue for the retailer due to this inaccurate weighing.
Several off scale item sensing devices have been proposed. One such system includes a light source that generates a light beam and a plurality of mirrors directing the light beam along a path around a perimeter of the weigh platter and then to a detector. The detector receives the light beam and an alarm coupled to the detector is operative for alerting an operator when the item is placed in the light beam path. Such a system requires system components be positioned above the surface of the weigh platter. These components tend to require precise optical alignment and/or placement and are subject to impact of items being passed through the scan volume interfering with the movement of items and impact may also cause misalignment of the components. Present inventors have thus recognized the need for an improved system for detecting off scale items.